August 22, 2007

Pro-Am collaboration to unveil the atmosphere of Venus

Results from an ongoing collaboration between amateur astronomers and the European Space Agency to support the Venus Express mission will be presented at the European Planetary Science Congress in Potsdam on Wednesday 22nd August.

Prof. Bernard Foing, Project Scientist for the SMART-1 mission, said, “Europe has now looked at the Moon, Mars and Venus and we have put our finger on Titan. These are great achievements. But for the future, it is not enough to briefly ‘kiss’ the surface of other solar system objects. We must bring them back to Earth for analysis.”

Silvia Kowollik, from the Zollern-Alb Observatory in Germany and one of the participants in the project, said, “This is the first time there’s been a European collaboration between amateur astronomers and scientists. In the United States, they have a long tradition and a lot of experience in this kind of work. In Europe we are just starting.”

Since its launch in 2006, ESA’s Venus Amateur Observing Project (VAOP) has invited amateur astronomers to submit scientifically useful images and data to support scientists working on the Venus Express mission. The amateur images, taken in the infrared, visible and ultraviolet bands, give a different, global perspective on features observed by the spacecraft, show a comparative view of the planet in various parts of the spectrum covered by instruments aboard Venus Express, and can also capture views of Venus that are hidden to the spacecraft in its orbit. The highly elliptical orbit of Venus Express means that the spacecraft moves slowly around the planet’s south pole but whips over the northern latitudes, so the ground-based images are especially important for observing features north of the equator.

Dr Thomas Widemann, who is participating in a parallel professional campaign of ground-based observations to support Venus Express said, “There have been huge advances in relatively cheaply available equipment, which means that amateurs can take images in wavelengths from infrared through to ultraviolet with impressive accuracy and content. These amateur observations are the last link in a chain that starts with Venus Express and continues with the professional ground-based activities. When joined together, all these observations will all help to peel back the atmosphere of Venus and reveal her mysteries.”

Developments in video astronomy have meant that amateurs can select and combine thousands of rapidly exposed video frames in order to cancel out the distorting effects of atmospheric turbulence.

Ms Kowollik said, “This has been a great experience for amateurs. Several observers in Germany have taken part and have gained considerable expertise in image processing. We are now looking forward to future Venus observation campaigns.”

The ultraviolet observations are of particular interest because scientists still do not know the chemical constituent of Venus’s atmosphere that causes the planet’s yellowish tinge. Dr Widemann said, “Something is absorbing the blue end of the visible spectrum. There are many theories.


Figure 1: U-Band filtered images of Venus taken using a 235mm Schmitt-Cassegrain SCT telescope and a SAC-8 CCD camera in video mode
An example of routine monitoring of Venus, with images taken at approximately the same time of day between the 8 March & 18 April 2004. Changing cloud structure is apparent on the planet. The resolution of individual images varies from day to day due to differences in the seeing conditions (atmospheric turbulence). Over the course of the 6 week observing period the phase and apparent diameter of the planet changed significantly. Credit: Jason Hatton